Dispenser for particulate material



Sept. 5, 1967 T. E. STERNS 3,339,808

DISPENSER FOR PARTICULATE MATERIAL Filed OC'C. 1, 1965 2 Sheets-Sheet 1 ll! III AIR 5 75 T E M 20 INVENTOR.

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Sept. 5, 1967 T. E. STERNS DISPENSER FOR PARTICULATE MATERIAL 2 Sheets-Sheet 2 Filed Oct. 1, 1965 INVENTOR.

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firfoknrsys United States Patent 3,339,808 DISPENSER FOR PARTICULATE MATERIAL Thomas E. Sterns, Rosemount, Minn., assignor to Ramsey Engineering Company, St. Paul, Minn., a corporation of Minnesota Filed Oct. 1, 1965, Ser. No. 492,065 8 Claims. (Cl. 222-196) This invention relates to the art of dispensing; and more particularly, the invention relates to a dispenser for controlling the rate of feed of pulverized or particulate solids from a bin or feed hopper or the like.

The dispenser according to the invention has particular utility in the handling of finely milled products such as bentonite or cement. These materials, and others like them, are quite diflicult to handle because they seldom flow freely. One of the common causes of erratic flow in such materials is the phenomenon called bridging, which is the formation of a compacted mass of the material in blocking relation to the hopper opening. Another undesirable phenomenon is flooding, which occurs when material flows too rapidly into the feed orifice, as when a bridge suddenly breaks. Still another problem in handling these materials resides in the fact that they are dusty and harmful if breathed.

It is an object of the invention, therefore, to provide a dispenser or dispensing valve for particulate products, which eliminates the major problem areas such as bridging, flooding, dusting and the like.

Another object of the present invention is to provide a pulsating or vibratory dispensing valve for particulate solid materials, together with a means for controllably actuating the valve to vary the rate of flow of dispensed material and for varying the amplitude and frequency of vibration of the valve to adapt it for handling different materials with different flow characteristics.

Still another object of the invention is to provide a vibratory dispensing valve constructed to provide a dusttight seal between the inlet and outlet thereof so as to minimize the health hazard from finely milled products.

Briefly described, the dispenser according to a preferred form of the invention comprises a combined valve plug and discharge spout secured in sealed but movable relation around a discharge orifice in the bottom of a feed hopper. The plug is spring biased into closed relation with the discharge orifice and is adapted to be opened by means of air pressure. The air system for actuating the valve includes means for alternately applying and relieving pressure so that a pulsating or vibratory effect is achieved. The dispenser also includes a discharge assisting means in the form of a rod fixed to the valve plug and extending upwardly through the discharge orifice into the interior of the hopper. The rod vibrates with the plug and thereby prevents the formation of any bridges or similar compa-ctions of material.

Other objects, advantages and the details of construction of a preferred embodiment of the invention will become apparent from the following description when read in conjunction with the accompanying drawingswherein:

FIGURE 1 is an elevational view showing the feed valve of the invention in place on a storage hopper;

FIGURE 2 is a vertical section through the valve, illustrating its details of construction; and

FIGURE 3 is a diagrammatic showing of the pneumatic actuating system.

As illustrated in FIGURE 1, the dispensing valve mechanism is generally indicated at as attached to the lower or feed end of a storage bin or hopper 12. The air system for actuating the valve is diagrammatically shown at 14 and the details of this system will appear hereinafter.

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Mechanism 10 consists of a stationary support means 15 and the vibratory valve and discharge spout assembly 17. Support means 15 includes a top flange 18 and a bottom flange 20 fixedly attached in spaced relation to top flange 18 by a plurality of spacer rods 21. Any number of spacer rods may be employed, but for purposes of clarity only two have been shown in the drawings.

As will appear more fully hereinafter, spout assembly 17 is connected to top flange 18 by a flexible tube or boot 22 so that the assembly 17 may move freely in the vertical direction indicated by the arrows 23 while maintaining a sealed condition from the bottom of the hopper 12 to the discharge end of the spout assembly 17. For vibrating the spout assembly 17, a pneumatic cylinder 25 is provided which is in fluid communication with the air system 14 over conduit 26.

The details of the dispensing mechanism 10 are illustrated in FIGURE 2. As shown there, top flange 18 is secured, as by welding, to a depending tube 29 in communication with the interior of the hopper 12. The lower free end 30 of tube 29 defines a discharge orifice and valve seat for cooperation with a valve plug 32, which is an integral part of the spout assembly 17.

Spout assembly 17 comprises an outer cylindrical housing 33 and a spout 34 extending transversely therefrom. Valve plug 32 is supported on a disc-shaped plate 36 and an inner housing 37 is secured around the periphery. of plate 36, as by welding. Outer housing 33 and inner housing 37 define an annular discharge zone therebetween. The bottom end of this Zone is closed by an annular plate 39, which is inclined as shown to direct material toward the spout 34.

As stated above, assembly 17 is connected to top flange 18 by a flexible boot 22. One edge of boot 22 is clamped to the upper edge of outer housing 33 by means of a clamping ring 40. The other edge of boot 22 is clamped to a ring 41, attached to top flange 18 by a second clamping ring 42. Convolutions 44 in boot 22 permit free movement of assembly 17 While maintaining the desired dust-sealed condition.

Plate 36 also supports a bridge-breaker rod 45. Typically, rod 45 has a head 47 thereon and may be passed through a suitable opening in valve plug 32 before the valve plug is assembled with plate 36. The valve plug itself will then hold the rod 45 in place. Rod 45 extends upwardly into the interior of hopper 12 Where it may act to agitate and break up any bridges or other compacted masses which may form in the material.

Pneumatic cylinder 25 is supported on bottom flange 20 in any desired manner. A commercially available cylinder, for example, has a shoulder 48 on the body thereof,

8 The cylinder may thus be inserted in an aperture 50 in bottom flange 20 with shoulder 48 resting on the upper surface of bottom flange 20. Cylinder 25 is arranged to have its piston rod 52 extending upwardly for reciprocating movement in the vertical direction as indicated by the arrows 53. The free end of piston rod 52 is attached to plate 36 in any suitable manner. A threaded connection with a lock nut as indicated at 55 is preferred.

The entire assembly 17 is spring biased upwardly to bring plug 32 into closing relation to the end 30 of tube 29. For this purpose, a spring 56 is provided in encircling relation to piston rod 52 and acting between the upper end 57 of cylinder 25 on the one hand and plate 36 on the other. Spring 56 may engage lock nut 55 as shown or it may engage the surface of plate 36 depending on the dimensions of the parts.

A pneumatic coupling fixture 60 is provided on cylinder 25 to which conduit 26 is attached to supply fluid under pressure to the interior of cylinder 25. Cylinder 25 is of conventional single-acting structure, piston rod 52 passing through a packing gland 61 to the interior of cylinder 25 where it is coupled to a piston 62. A suitable sealing means, such as an O-ring 63, is provided between the piston and cylinder. Air pressure supplied to the zone above piston 62 will move the piston and consequently the entire spout assembly 17 downwardly, compressing the spring 56. To permit this movement, the zone bel W the piston is vented as by an aperture 64 in the cylinder 25.

FIGURE 3 illustrates the pneumatic system 14 which is utilized in the practice of the present invention. Fluid pressure is supplied to cylinder 25 from a pump generally shown at 65. From pump 65, the fluid circuit extends through a conduit 66 to a conventional pressure regulator 68, then through conduit 70 to a pulsating means 72, and then through conduit 26 to cylinder 25. Regulator 68 may take any desired form, but for purposes of illustration has been shown as a diaphragm type regulator having a knob 69 for varying the pressure supplied to conduit 70.

In order to pulsate or vibrate the spout assembly 17 in a controlled manner, the means 72 is interposed between the regulator 68 and the cylinder 25. In the illustrated embodiment, means 72 takes the form of a solenoid actuated spool valve. As shown, valve 72 has a spool 73 which is spring biased to the upward position by a spring 74 and which is moved downwardly when current flows through a solenoid 76 connected to spool 73. In its downward position, spool 73 interconnects conduits 70 and 26 to supply fluid under pressure to cylinder 25. In its upward position, spool 73 cuts off the flow of fluid from conduit 70 and establishes communication from conduit 26 to atmosphere through a conduit 77 containing an orifice plate 78. It will be understood that the valve parts are dimensioned so that a minimum amount of spool travel is required to change the fluid connections.

Solenoid 76 is energized in a pulsating manner by a control circuit 80 which is provided with means for independently varying the duration of the on and off times of the solenoid. Control is provided by a bi-stable pair of silicon controlled rectifiers SCRl and SCR2 which are alternatively triggered to conduction by unijunction transistors UJT1 and UJT2 respectively. SCRl is in series with the coil of solenoid 76 and the solenoid will be actuated when SCRI conducts.

SCRl and SCR2 are triggered by the voltages produced across their gate-to-cathode resistors 81 and 82 respectively as their associated capacitors 83 and 84 are alternately discharged by the unijunction transistors UJT1 and UJT2. A variable resistor 85 controls the duration of current flow through solenoid 76 and a variable resistor 86 controls the off time of the solenoid. The additional elements in the circuit are a coupling capacitor 87, biasing resistors 88 and 89 and a balancing resistor 90. The operation of the circuit is as follows.

Assuming that SCR2 is conducting and SCRl is not conducting, at the instant that SCRl is triggered, there will be a rapid decrease in voltage at its anode which is coupled through capacitor 87 to the anode of SCR2, causing SCR2 to cease conducting. This results in a reduction in the current flowing in resistor 90 and permits the voltage across resistor 90 and variable resistor 85 to produce a charging current into capacitor 84. When capacitor 84 reaches a voltage determined by the characteristics of unijunction transistor UJTZ, it discharges through the emitter lower-base junction of UJTZ and the resistor 82, producing a voltage across resistor 82 which is sufficient to trigger SCR2. The time interval between the triggering of SCRl and the subsequent triggering of SCR2 is determined by the value of the capacitor 84 and the value of the resistor 85, so that resistor 85 provides an adjustment for the on time of solenoid 76.

The off interval of solenoid 76 begins with the triggering of SCR2. The circuit operates in the same manner as described above, conduction of SCR2 causing cessation of current flow in SCRl and initiation of the charging cycle for capacitor 83. When the capacitor 83 has charged to the extent permitted by UJT1, it discharges through the emitter lower-base junction of UJT1 to establish a triggering voltage across resistor 81, thereby triggering SCRl. The charging time of capacitor 83 is controlled by variable resistor 86, which therefore is the adjustment for the off time of solenoid 76.

In the operation of the present valve actuation system, the manner in which assembly 17 oscillates or vibrates is a function of the source pressure as established by regulator 68, the durations of the on and off times of solenoid 76, the strength of spring 56 and the size of the bleed aperture in orifice plate 78. It should be apparent that under static conditions, in the pressure transmitting position of spool 73, a pressure P would cause a displacement a of the piston 62 and assembly 17 to establish the equilibrium situation in which PA :kd

where A is the effective area of piston 62 and k is the constant of spring 56. In the bleed position of spool 73, the piston and the assembly 17 will move upwardly as air bleeds from conduit 77 at a rate dependent on the size of the aperture in orifice plate 78.

Under actual operating conditions, the adjustment of resistors and 86 becomes important in that the time that spool 73 is in each of its operative positions will determine the actual extent of movement of the piston and consequently of spout and valve assembly 17. Thus, the piston can move downwardly toward the equilibrium position only as long as pressure is applied to it and can move upwardly only as long as the valve 72 is vented. Accordingly, both the frequency and amplitude of oscillation of the piston are determined by the times that spool 73 remains in each of its positions. The maximum displacement of the piston 62, and consequently the maximum size of the main discharge opening, can be varied by adjusting either the supply pressure or the on time of solenoid 76. The off time adjustment and the size of the opening in orifice plate 78, on the other hand, permit variation of the frequency and amplitude of the reciprocating action.

The dispensing apparatus as described fulfills all the objects and purposes set forth above. The device efiiciently handles such diflicult materials as bentonite or finely milled cement, since the bridge breaker rod acts to keep material flowing to the discharge orifice, and the vibratory action of the spout and valve assembly promotes the flow of material out of the spout. Moreover, the action of the spout assembly may be easily varied to suit different materials. All this is accomplished in a substantially dustfree manner.

Obvious variations and modifications of the invention will become apparent to those skilled in the art after reading the above disclosure. Accordingly, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as herein specifically described.

I claim:

1. A dispenser for controlling the rate of flow of particulate material from a bin comprising a discharge tube extending downwardly from said bin, said discharge tube being 1n communication with the interior of said bin and having a free lower end defining a discharge orifice, a

spout and valve assembly surrounding said discharge tube, said spout and valve assembly comprising a housing and a spout extending transversely therefrom, a plug member carried by said housing, said plug member having a tapered surface thereon in flow controlling relation to said discharge orifice, a flexible coupling between said housing and said bin whereby a sealed condition is maintained between said discharge orifice and the discharge end of said spout, and a rod connected to said spout and yalve assembly for movement therewith, said rod extendmg through said discharge tube to the interior of said bin, spring means normally forcing said spout and valve assembly into closing relation to said discharge orifice, fluid motor means comprising a cylinder fixedly mounted with respect to said bin and a piston and piston rod movable in said cylinder under the force of fluid pressure, said piston rod being connected to said spout and valve assembly, and means for supplying fluid pressure to said cylinder to move said piston and said spout and valve assembly away from discharge closing relation against the action of said spring, said pressure supplying means including a pulsator means for alternately and sequentially supplying fluid pressure to said cylinder and venting said cylinder to the atmosphere.

2. A dispenser as defined in claim 1, said fluid pressure supplying means further including an adjustable regulator for varying the applied pressure, said pulsator means comprising a pulsator valve having means for connecting said fluid motor means alternately to said regulator and to a venting conduit having an orifice plate having an aperture of predetermined size therein, and means for actuating said pulsator valve, including means for varying the times during which said pulsator valve remains in its pressure transmitting and its venting conditions.

3. A dispenser as defined in claim 2, said pulsator valve consisting of a spool valve, solenoid means for moving said spool valve to its pressure transmitting condition and spring means for normally biasing said spool valve to its venting condition, said actuating means comprising electric circuit means having means for adjustably periodically energizing and deenergizing said solenoid.

4. A dispenser for controlling the rate of feed of pulverized solids from a bin comprising a discharge valve assembly including means defining a discharge orifice communicating with the interior of said bin, at vibratory plug member normally closing said orifice, and an agitating rod fixed to said plug member and extending through said discharge orifice to the interior of said bin, housing means surrounding said plug member and having a spout extending transversely therefrom, said housing means defining an annular discharge zone around said plug member, said housing means being fixed to said plug member and movable therewith, flexible sealing means extending between said housing means and said bin, said sealing means being in surrounding relation to said dis charge orifice defining means, whereby said discharge valve assembly is sealed between its inlet at the bin discharge orifice and its outlet at the spout, fluid motor means for moving said plug member to open said discharge orifice and means to move said plug member in direction to close said orifice to vibrate said plug member and agitating rod, and means for supplying regulated pulsating fluid pressure to said fluid motor means for operating the same, said pressure supplying means including pulsator means for alternately and sequentially transmitting fluid pressure to said fluid motor means and venting said fluid motor means to atmosphere.

5. A dispenser as defined in claim 4, said fluid pressure supplying means further including an adjustable regulator for varying the applied pressure, said pulsator means comprising a pulsator valve having means for connecting said fluid motor means alternately to said regulator and to a venting conduit having an orifice plate having an aperture of predetermined size therein, and means for actuating said pulsator valve, including means for varying the times during which said pulsator valve remains in its pressure transmitting and its venting conditions.

6. A dispenser as defined in claim 5, said pulsator valve consisting of a spool valve, solenoid means for moving said spool valve to its pressure transmitting condition and spring means for normally biasing said spool valve to its venting condition, said actuating means comprising electric circuit means having means for adjustably periodically energizing and deenergizing said solenoid.

7. A dispenser for controlling the feed of particulate material from a bin comprising a discharge valve assembly including means defining a discharge orifice communicating with the interior of the bin, a housing separate from the bin, a plug member mounted at the exterior of said bin in sealing relationship to said housing to form a chamber, said plug member normally closing said orifice, a flexible bellows sealingly attached between the bin and the housing and surrounding the orifice, an outlet defined in the housing and leading from the chamber formed in said housing, an agitating member fixed to said plug member and extending through said discharge orifice to the interior of said bin, fluid motor means for moving said plug member and said housing in direction away from said bin to open said discharge orifice, means to move said plug member and housing in direction to close said orifice and means for supplying fluid pressure to said fluid motor means including pulsator means for alternately and sequentially transmitting fluid pressure to said fluid motor means to move said plug to open the orifice and to release the fluid motor means while the plug is being moved to close the orifice.

8. A dispenser as defined in claim 7 wherein the means to return the plug to its normal position comprises a spring biasing the plug member toward the orifice.

References Cited UNITED STATES PATENTS 2,325,970 8/1943 Myers 222-196 X 2,526,735 10/1950 Duce 222-196 2,911,901 11/1959 Totten et al 222-196 X 3,204,832 9/1965 Barber 222-196 FOREIGN PATENTS 891,135 3/1962 Great Britain.

ROBERT B. REEVES, Primary Examiner. HADD S. LANE, Examiner. 

7. A DISPENSER FOR CONTROLLING THE FEED OF PARTICULATE MATERIAL FROM A BIN COMPRISING A DISCHARGE VALVE ASSEMBLY INCLUDING MEANS DEFINING A DISCHARGE ORIFICE COMMUNICATING WITH THE INTERIOR OF THE BIN, A HOUSING SEPARATE FROM THE BIN, A PLUG MEMBER MOUNTED AT THE EXTERIOR OF SAID BIN IN SEALING RELATIONSHIP TO SAID HOUSING TO FORM A CHAMBER, SAID PLUG MEMBER NORMALLY CLOSING SAID ORIFICE, A FLEXIBLE BELLOWS SEALINGLY ATTCHED BETWEEN THE BIN AND THE HOUSING AND SURROUNDING THE ORIFICE, AN OUTLET DEFINED IN THE HOUSING AND LEADING FROM THE CHAMBER FORMED IN SAID HOUSING, AN AGITATING MEMBER FIXED TO SAID PLUG MEMBER AND EXTENDING THROUGH SAID DISCHARGE ORIFICE TO THE INTERIOR OF SAID BIN, FLUID MOTOR MEANS FOR MOVING SAID PLUG MEMBER AND SAID HOUSING IN DIRECTION AWAY FROM SAID BIN TO OPEN SAID DISCHARGE ORIFICE, MEANS TO MOVE SAID PLUG MEMBER AND HOUSING IN DIRECTION TO CLOSE SAID ORIFICE AND MEANS FOR SUPPLYING FLUID PRESSURE TO SAID FLUID MOTOR MEANS INCLUDING PULSATOR MEANS FOR ALTERNATELY AND SEQUENTIALLY TRANSMITTING FLUID PRESSURE TO SAID FLUID MOTOR MEANS TO MOVE SAID PLUG TO OPEN THE ORIFICE AND TO RELEASE THE FLUID MOTOR MEANS WHILE THE PLUG IS BEING MOVED TO CLOSE THE ORIFICE. 